I am indecisive about choice due to room size

Easiest way to get good sound in a square room. Use active speakers with digital control like Genelec, Dutch and Dutch,  Kii, new company GGNTKT might be another. There are others you can research. I've used passive speakers with outboard control it helps but isn't as good. You'll need less room treatments and get better results. One thing you don't need is a passel of subwoofers in that small room you can get all the bass you need for music with a  couple of Genelec 8361A. 

I am in a 12x12 with focal 1028be and Hegel h360 and still sometimes wish for more speaker. I think it depends on your listening style as much as anything else.

Many Japanese audiophiles do something highly counter-intuitive: They use large horn loudspeakers in small rooms. Speakers conceptually similar to the Altec Model 19.

But maybe they are onto something: These large-format horn loudspeakers have fairly narrow and unusually uniform radiation patterns. So they put less energy into the early reflections, and in general the narrow radiation pattern results in the direct sound dominating over the reflections. And the uniform radiation pattern means that reflections will be spectrally correct, such that they support (rather than degrade) the timbre.

I’m not necessarily suggesting a pair of Altec Model 19’s, but rather advocating the general concept of starting out with controlled-pattern loudspeakers when the room is challenging.

Also, if this is a dedicated audio room, given its square footprint, I suggest setting up your system on a diagonal. This geometrically precludes early sidewall reflections. It is the earliest reflections which most strongly convey a "small room signature". If we’d rather hear the acoustic signature of the recording venue, then in a small room the earliest reflections are the ones we most want to minimize. In my opinion.

And maybe even try your system ALMOST on a diagonal... like perhaps off by ten degrees.  This puts your woofers each at a different distance from all of the walls, which may make a worthwhile improvement in the bass region. 

Duke

The truth is Duke and I are going about the problem from complementary positions.

The better controlled dispersion you can have, the less room treatment you need.

Still, I believe you are better off treating the room first, before undertaking the speaker swap game.